FILE - This April 24, 2005 file photo shows Pope Benedict XVI,center, holding a cross as he celebrates his installment Mass in St. Peter's Square, at the Vatican, Sunday, April 24, 2005. Benedict XVI announced Monday, Feb. 11, 2013, that he would resign on Feb. 28 because he was simply too infirm to carry on - the first pontiff to do so in nearly 600 years. The decision sets the stage for a conclave to elect a new pope before the end of March. (AP Photo/Andrew Medichini, files)

Gallery: A look back at Pope Benedict XVI

The 85-year-old pope announced his decision in Latin during a meeting of Vatican cardinals.

“After having repeatedly examined my conscience before God, I have come to the certainty that my strengths due to an advanced age are no longer suited to an adequate exercise of the Petrine ministry,” he told the cardinals.

Benedict, the first pontiff to resign in nearly 600 years, emphasized that carrying out the duties of being pope — the leader of more than a billion Roman Catholics worldwide — requires “both strength of mind and body.” He says he is simply too infirm to carry on.